1. Field of the Invention
This application relates generally to networking devices, and, more specifically, networking devices that present different virtual router configurations to different end users, classes of service or packets.
2. Related Art
Virtual router functionality refers to the capability of the same physical networking device of presenting different virtual router configurations to different end users, classes of desired service, or packets. As a result of this capability, the same physical device appears as a plurality of different virtual routers.
Current networking devices provide virtual router functionality through certain virtual identifiers, for example, VLAN and virtual port fields, which may be obtained or derived from information in an incoming packet. More specifically, current devices perform core virtual router functions responsive to these virtual identifiers. In fact, the VLAN field, which designates a virtual LAN, a collection of network elements that may be physically disparate but are logically related such that they may be considered part of the same LAN for OSI layer two routing/switching purposes, impacts almost every core virtual router function. Similarly, the virtual port field, which is the combination of the VLAN field and the ingress port field, also impacts other core virtual router functions.
This approach worked fine as long as network usage or standards remain static, and changes in the virtual identifier type and format occurred infrequently. However, in current TCP/IP or UDP/IP networks, where network usage and standards are dynamic and constantly evolving, the approach is problematic as changes in virtual identifier type or format, for example, VLAN type or format, occur frequently. Recently, for example, a 24-bit “super” VLAN field, the ESID field, was recognized as a valid Ethertype, marking an addition to the 12-bit VLAN field that had existed before. Therefore, with the current approach, the device has to be entirely retooled on a relatively frequent basis in order to provide the same virtual router functionality as before.
Another problem with the current approach is that it is not scaleable with an increase in the number of VLANs that may need to be accommodated. In the current approach, for example, an increase in the size of the VLAN field to allow for an increase in the number of VLANs multiplies in direct proportion the number of virtual port state tables, i.e., a tables indicating the state of each virtual port in the router, as well as other resources, that need to be maintained.